Rooftop vent for reducing pressure under a membrane roof

Abstract

Membrane roofs are susceptible to damage in high winds. Wind can lift a membrane roof from a building and cause it to tear or become damaged. The present roof vent prevents liftoff and damage by reducing the air pressure under the membrane during high winds. The present roof vent has two opposed convex domes separated by a gap. Wind blowing across the roof flows between the domes where it accelerates and creates a region of low pressure according to the Venturi effect. The lower dome has an opening at the gap so that the low pressure is applied to the space under the membrane roof. Therefore, when wind blows across the roof, the vent draws air from under the membrane and the membrane is pressed against the roof, preventing liftoff.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is related to U.S. Provisional Patent Application Ser. No. 60 / 466,441 filed Apr. 30, 2003, and the complete contents of that application is herein incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to rooftop vents, and, more specifically, to a vent for reducing pressure under a membrane roof during windstorms.BACKGROUND OF THE INVENTION[0003]Membrane roof systems are commonly used in low-slope roofs. A membrane roof typically comprises a rubber or plastic (e.g., made of PVC) sheet that provides a moisture and vapor barrier. Membrane roofs are relatively inexpensive to install and consequently the use of membrane roof systems has been expanding in recent years.[0004]One problem with membrane roofs is that they are susceptible to damage from high winds. High winds create a reduced air pressure on the top surface of the membrane, which cause it to lift from the building. A membrane...

AI Technical Summary

Benefits of technology

[0008]The present invention provides a roof vent for use with membrane roofs. The present vent includes a lower dome and an upper dome separated by a gap. The domes are shaped and positioned so that the distance between the domes is smallest at the center and greatest at the periphery. This structure induces the Venturi effect when wind blows between the domes. The lower dome has a port that is open to a space under a roof membrane. When wind blows through the present roof vent, low pressure is created at the port by the Venturi effect, and the low pressure is applied to the space under the membrane.

[0011]The vent can include a drip edge on the upper dome to prevent water from dripping into the port. The lower dome can include a drip pan and drain to collect and exhaust undesired water that falls into the port.

[0013]The present invention also includes a membrane roof system having a roof membrane in combination with the present roof vent. In the present membrane roof system, a porous layer or grooves can be provided under the membrane so that air can flow under the membrane. This feature maximizes the area of reduced pressure and helps prevent trapped pockets of air under the membrane.

Problems solved by technology

One problem with membrane roofs is that they are susceptible to damage from high winds.

High winds create a reduced air pressure on the top surface of the membrane, which cause it to lift from the building.

A membrane roof lifted from the subroof can be torn from the building or damaged in other ways.

Hence, one of the challenges of designing membrane roof systems is providing an attachment method strong enough to prevent uplift of the membrane during high wind conditions.

These methods have a tendency to increase heat transmission through the roof, which increases heating and cooling costs.

Also, these methods are not completely reliable in very high winds.

However, both these solutions require air-tight deck assemblies for efficient operation and have a relatively high manufacturing cost.

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